1. Field of the Invention
The present invention relates to a stereoscopic image characteristics examination system for examining the characteristics of a stereoscopic image photographed by a stereo camera to generate correction data.
2. Description of the Related Art
Hitherto, a stereoscopic image recognition technique using a plurality of cameras is known as a technique of three-dimensionally recognizing a space. The stereoscopic image recognition technique is applied to, for example, an obstacle detecting apparatus which is mounted on a vehicle such as an automobile. According to this technique, while the distance between the automobile and a solid object being detected, an obstacle which lies ahead and the shape of a road are recognized, thus contributing to the improvement of safety.
Generally, apparatuses using the stereoscopic image recognition technique use a method for searching for a matching point on images captured by cameras constituting a stereo camera to obtain a parallax therebetween and then calculating distance information from the parallax. In order to maintain the recognition capability of the apparatus, it is necessary to ensure the reliability of matching point search and parallax detection accuracy.
Accordingly, in Japanese Unexamined Patent Application Publication No. 11-325889, the present applicant has proposed a technique of correcting a nonlinear positional deviation between images captured by a stereo camera to align the optical axes of the images, resulting in uniform base line for matching search. In Japanese Unexamined Patent Application Publication No. 2001-91245, the present applicant has proposed a technique of correcting a parallax detection error caused by the characteristics and variations of optical systems such as lenses. Furthermore, in Japanese Unexamined Patent Application Publication No. 2001-92968, the present applicant has proposed a technique of correcting a matching-search start position so that an appropriate search range can be set depending on a position on an image.
However, maintaining the capability of the stereoscopic image recognition apparatus requires a system which can obtain comprehensive and high-accurate correction data for the characteristics of stereoscopic images for each apparatus prior to shipment of the apparatus or upon readjustment after the shipment. Furthermore, it is preferable that correction data be obtained in a system, which is constructed as simple as possible, to eliminate a factor causing an increase of the cost of the apparatus.